Manufacturing processes for automobiles have evolved from one that utilized MIG welding processes, i.e. a welding process in which a line of molten material is deposited by the welder in joining two pieces of metal together. Spot-welding, a process involving the passage of electrical current between two electrodes to melt and join two pieces of metal placed between the electrodes, is being utilized in a greater degree in the manufacturing of automotive vehicles. Spot-welding requires a body structure design that is conducive to being manufactured using the spot-welding process. For example, if two tubular members are being spot-welded, access to the adjoining walls of the two tubular members by the spot-welder electrodes must be provided.
The joinder of hydroformed body structure members presents a problem for body structure construction in automobiles. If the body structure members are positioned in a parallel orientation, the contiguous sides of the two body structure members can be spot-welded together with the electrodes being inserted through openings formed during the hydroforming process in the respective opposing sides of the body structure members.
Since hydroformed body structure members are tubular in configuration, the body structure members have open ends. Therefore, welding the connection of a body structure member that is butted against a lateral side of another body structure member presents a welding problem that is conventionally solved by MIG welding processes with the edges of the butted body structure member being welded to the sides of the adjoining body structure member. If the body structure member being butted against the lateral side of the other body structure member is physically smaller that the other body structure member, the smaller body structure member can be inserted into an opening formed in the other body structure member so that the smaller body structure member butts or aligns with the opposing surface of the larger body structure member and the respective sides of the body structure members can be spot-welded together if the body structure members are sized appropriately. However, such welding techniques do not work if the two body structure members are not sized to snuggly fit together before being spot-welded.
In U.S. Pat. No. 5,018,781, granted to Hideyuki Kumasaka, et al on May 28, 1991, the front roof rails, rear roof rails and side roof rails comprise separate components that are connected together using mounting flanges that are formed into the side rail components. A mounting bracket is disclosed in U.S. Pat. No. 5,226,696, granted to Ulrich Klages, et al on Jul. 13, 1993, but the configuration requires that the roof side rail be notched to receive the bracket, which requires added manufacturing expense and weakens the roof side rail.
A cup-shaped damper mounting portion and a bracket portion are welded together to form a rear damper base that is connected to the rear pillar in U.S. Pat. No. 6,073,993, issued on Jun. 13, 2000, to Syuichiro Iwatsuki, et al; however, this structure is not utilized on an automotive roof structure. The body structure for a sport utility vehicle disclosed in U.S. Pat. No. 6,099,362, issued to Alan Hine on Aug. 8, 2000, teaches a U-shaped joint connecting mechanism that are welded to the side rail members and a pair of rail plates. This patent suggests that this structure can be utilized for roof bows and headers to improve torsional rigidity.
The prior art described above does not suggest the connection of a transversely extending formed and convoluted roof cross member, such as a header or a bow, to a hydroformed tubular member in a manner that would add strength to the joint. Accordingly, it would be desirable to provide an apparatus that would be operable to mount a shaped transverse roof cross member to tubular side rails.